Systems, methods and apparatus for calibrating differential air pressure devices

ABSTRACT

Methods, apparatus, and systems for calibrating differential air pressure systems are described. The methods, apparatus, and systems may be adapted for physical training of an individual, e.g. as a training tool to improve performance or as a physical therapy tool for rehabilitation or strengthening. The differential air pressure systems comprise a chamber for receiving at least a portion of a user&#39;s body. In one embodiment, a method for calibrating a differential air pressure system for predicting effective body weight of a user versus system pressure is described. In certain variations, the methods, apparatus and systems may comprise adjusting pressure in the system until one or more force values are reached. The methods described herein may comprise determining a relationship between body weight force and pressure, allowing the user to set a pressure or a parameter correlated with pressure to achieve a desired effective body weight.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 60/999,061, entitled “METHOD FOR DETERMINING UNLOADING SETTINGS IN A DIFFERENTIAL AIR PRESSURE DEVICE VIA PAIN TITRATION,” filed on Oct. 15, 2007, U.S. Provisional Patent Application Ser. No. 60/999,102, entitled “ADJUSTABLE SUPPORT FOR A DIFFERENTIAL AIR PRESSURE DEVICE” and filed on Oct. 15, 2007, U.S. Provisional Patent Application Ser. No. 60/999,101, entitled “ADJUSTABLE ORIFICE FOR A DIFFERENTIAL AIR PRESURE DEVICE” and filed on Oct. 15, 2007, U.S. Provisional Patent Application Ser. No. 60/999,060, entitled “METHOD FOR APPLYING A DIFFERENTIAL AIR PRESSURE DEVICE IN THE FIELD OF PEDIATRICS, OBESITY, AND CARDIAC DISEASE” and filed on Oct. 15, 2007, each of which is incorporated herein by reference in its entirety. This application is related to U.S. patent application Ser. No. ______, entitled “SYSTEMS, METHODS AND APPARATUS FOR DIFFERENTIAL AIR PRESSURE DEVICES” (Attorney Docket No. 8038.P002) and filed concurrently herewith, which is incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention relates to differential air pressure devices. More particularly, the present invention relates to systems, methods and apparatus for calibrating a differential air pressure device.

BACKGROUND OF THE INVENTION

Gravity produces forces on the body. Methods of counteracting these forces have been devised for therapeutic as well as physical training uses. One way to counteract the effects of gravity on a body is to attach elastic cords at the waist and/or shoulder to produce either a positive or negative vertical force on the individual.

Other systems may use differential air pressure to simulate a low gravity effect. Some methods of calibrating devices that counteract gravitational forces involve determining pressure compared to body weight are described in U.S. Patent Publication No. 2007/0181121, which is incorporated herein by reference in its entirety.

A need exists for improved devices and systems that can reduce the effects of gravity on a body, and in particular for improved devices and systems that can be calibrated, and methods for calibrating such improved devices and systems.

SUMMARY OF THE INVENTION

Methods, apparatus, and systems for calibrating differential air pressure systems are described herein. In general, the differential air pressure systems comprise a chamber for receiving at least a portion of a user's body, e.g. a lower portion of the body, including legs and hips. The methods, apparatus, and systems in certain variations can be adapted for physical training of an individual, e.g. as a training tool to improve performance, or as a physical therapy tool for rehabilitation or strengthening. In some embodiments, methods for calibrating a differential air pressure system described here may be used for predicting effective body weight of a user versus system pressure (pressure in a chamber housing the user's body portion).

As used herein, the notation (x, y) in the context of a data point is meant to referring to the value of y that corresponds to that value of x. For example, as used herein, a (pressure, force) data point refers to the force or load experienced by a user at that system pressure.

In some embodiments, methods for calibrating a differential air pressure apparatus or system comprise adjusting pressure in a chamber that surrounds at least a portion of a user's body, e.g. lower body, until body weight force on the user reaches a target force value, and measuring the chamber pressure at that target force value to generate a first (pressure, force) data point. The methods include using the first (pressure, force) data point with at least one other (pressure, force) data point to determine a relationship between body weight force experienced by the user and pressure in the chamber.

The target force value used in the methods may be a preset force value, or the target force value may be determined by the system for an individual user. When the target force value is determined for an individual user, the target force value may be stored by the system for subsequent use by the same individual user.

In some variations, the at least one other (pressure, force) data point may include a data point obtained at ambient pressure (i.e. zero system differential pressure), and thus may be the data point (0, user's body weight at ambient pressure).

Apparatus to predict effective body weight of a user as a function of system pressure are described. The apparatus comprise a differential air pressure system comprising a chamber configured to surround at least a portion of a user's body, e.g. a user's lower body. Processing logic coupled with the differential air pressure system is configured to adjust pressure in the chamber until body weight force on the user reaches a target force value, to measure the chamber pressure at the target force value to determine a first (pressure, force) data point, and to determine body weight force experienced by the user as a function of pressure in the chamber using the first (pressure, force) data point.

Other variations of methods for calibrating a differential air pressure system are described herein. The methods comprise adjusting pressure in a chamber of a differential air pressure system, the chamber surrounding at least a portion of a user's body. The methods comprise adjusting pressure in the chamber and receiving a pain indication supplied by a user as a function of pressure, and constructing a pressure versus pain relationship for the user.

In some variations of the methods, the differential air pressure system comprises an exercise machine, and the pressure versus pain relation can be used to control operation of the exercise machine. For example, in some variations the exercise machine can comprise a treadmill, and the pressure versus pain relationship can be used to control at least one of a speed of the treadmill and an inclination of the treadmill. In some variations, the exercise machine can comprise a stepper machine or a stationary bicycle, and the pain versus pressure relationship can be used to control a resistance of the stepper machine or the stationary bicycle.

Other variations of apparatus to predict effective body weight of a user versus system pressure are described herein. The apparatus comprise a differential air pressure system that, in turn, comprises a chamber configured to receive and surround at least a portion of a user's body and a user interface. The apparatus also comprises a processor coupled with the differential air pressure system. The processor is configured to adjust pressure in the chamber, to receive a pain indication from the user via the user interface, and to construct a pain versus chamber pressure relationship for the user. In some variations of the apparatus, the pain versus chamber pressure relationship can be used to control operation of an exercise machine that is included in the differential air pressure system.

Still more methods for calibrating a differential air pressure system for predicting effective body weight of a user versus system pressure are described. The methods comprise surrounding at least a portion of a user's body with a chamber of a differential air pressure system, wherein the differential air pressure system comprises a sensor configured to sense whether the user's body within the chamber is in physical contact with a surface. The methods further comprise adjusting pressure in the chamber until a lift-off pressure is reached, wherein the lift-off pressure is a pressure at which the sensor detects a break in the physical contact between the user's body and the surface. The methods comprise using the lift-off pressure to calibrate the differential air pressure system. In some variations of the methods, the lift-off pressure can be used to determine a chamber pressure required to result in a desired effective body weight for the user. In certain variations, the lift-off pressure can be used to determine a maximum safety chamber pressure for the user to prevent lift-off during usage.

Still more variations of apparatus for predicting effective body weight of a user versus system pressure are described. In these variations, the apparatus comprise a differential air pressure system comprising a chamber configured to receive and surround at least a portion of a user's body and a sensor configured to detect whether the user's body within the chamber is in physical contact with a surface. The apparatus further comprise a processor coupled with the differential air pressure system, wherein the process is configured to inflate the chamber of the differential air pressure system and to measure a lift-off pressure at which the sensor detects that physical contact between the user's body and the user's body and the surface has been broken.

Still more methods for calibrating a differential air pressure system for predicting effective body weight of a user versus system pressure are described herein. The methods comprise using gas to pressurize a chamber in a differential air pressure system, the chamber surrounding at least a portion of a user's body. The methods comprise using a flow rate of the gas into and/or out of the chamber to determine the pressure in the chamber. For example, a valve position or opening size in an exhaust valve used to control gas flow rate out of the chamber can be used to determine pressure in the chamber. In some variations, power (voltage and/or current) used by a blower pumping gas into the chamber may be used to determine pressure in the chamber.

Additional methods for calibrating a differential air pressure system for predicting effective body weight of a user versus system pressure are described. The methods comprise measuring an effective body weight of a user, the user having at least a portion of the user's body surrounded by a chamber of a differential air pressure system, by measuring a startup power (voltage and/or current) of a motor of an exercise machine supporting the user's body within the chamber. The methods comprise correlating the effective body weight of the user with chamber pressure. In some variations, the chamber pressure can be determined using a flow rate of gas into and/or out of the chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated into and constitute a part of this specification, illustrate one or more embodiments of the present invention and, together with the detailed description, serve by way of illustration and not by limitation to explain the principles and implementations of the invention.

In the drawings:

FIG. 1 is a block diagram schematically illustrating an example of a differential air pressure system that can be used for exercise in accordance with one embodiment.

FIG. 2 is a block diagram schematically illustrating another example of a differential air pressure system that can be used for exercise in accordance with another embodiment.

FIG. 3 is a flow diagram schematically illustrating an example of a method for calibrating a differential air pressure system, e.g. a differential air pressure system as illustrated in FIG. 1 or 2.

FIG. 4 is a flow diagram schematically illustrating another example of a method for calibrating a differential air pressure system, e.g. a differential air pressure system as illustrated in FIG. 1 or 2.

FIG. 5 is a flow diagram schematically illustrating yet another example of a method for calibrating a differential air pressure system, e.g. a differential air pressure system as illustrated in FIG. 1 or 2.

FIG. 6 is a flow diagram schematically illustrating still another example of a method for calibrating a differential air pressure system, e.g. a differential air pressure system as illustrated in FIG. 1 or 2.

FIG. 7 is a flow diagram schematically illustrating another example of a method for calibrating a differential air pressure system, e.g. a differential air pressure system as illustrated in FIG. 1 or 2.

FIG. 8 is a flow diagram schematically illustrating another example of a method for calibrating a differential air pressure system, e.g. a differential air pressure system as illustrated in FIG. 1 or 2.

FIG. 9 provides a diagram of an example of a differential air pressure system.

FIG. 10 provides a diagram of another example of a differential air pressure system.

DETAILED DESCRIPTION

Those of ordinary skill in the art will realize that the following detailed description of the present invention is illustrative only and is not intended to be in any way limiting. Other embodiments of the present invention will readily suggest themselves to such skilled persons having the benefit of this disclosure. Reference will now be made in detail to implementations of the present invention as illustrated in the accompanying drawings. The same reference indicators will be used throughout the drawings and the following detailed description to refer to the same or like parts. Unless clearly indicated otherwise explicitly or by context, the singular referents such “a,” “an”, and “the” are meant to encompass plural referents as well.

In the interest of clarity, not all of the routine features of the implementations described herein are shown and described. It will, of course, be appreciated that in the development of any such actual implementation, numerous implementation-specific decisions must be made in order to achieve the developer's specific goals, such as compliance with application- and business-related constraints, and that these specific goals will vary from one implementation to another and from one developer to another.

In any variation described herein, any component, any process step, and/or any data structure may be implemented using any suitable type of operating system (OS), computing platform, firmware, computer program, computer language, and/or general-purpose machine described herein, presently known, or later discovered. Variations of the methods described herein can, for example, be run as a programmed process running on processing circuitry. If used, such processing circuitry can take the form of numerous combinations of processors and operating systems, or can be configured as a stand-alone device. Methods and processes described herein can be implemented as instructions executed by such hardware, hardware alone, software, software alone or any combination thereof. The software, if used, may be stored on a program storage device readable by a machine.

In addition, those of ordinary skill in the art will recognize that devices of a less general purpose nature, such as hardwired devices, field programmable logic devices (FPLDs), including field programmable gate arrays (FPGAs) and complex programmable logic devices (CPLDs), application specific integrated circuits (ASICs), or the like, may also be used without departing from the scope and spirit of the inventive concepts disclosed herein.

Embodiments of the present invention are described herein in the context of systems, methods and apparatus for using and calibrating air pressure in differential air pressure systems. In the methods, the differential air pressure system comprises a chamber for receiving and surrounding at least a portion of a user's body, e.g. a user's lower body including legs and hips. Any of the methods described herein for calibrating a differential air pressure system can include predicting an effective body weight of a user based on a system pressure, e.g. by extrapolation and or interpolation using a relationship between body weight force and chamber pressure determined during the calibration process.

When a portion of an individual's body is surrounded by a sealed chamber, pressure in the chamber can be changed to adjust force on the enclosed portion of the body, which in turn can affect force on the user's body as a whole. For example, the chamber can be pressurized to reduce gravitational force on the individual. There, pressure in the chamber can function to unweight or unload the individual from the normal effects of gravity. To control and/or quantify the amount of force experienced by a user, e.g. during exercise or rehabilitation, the pressure in the chamber can be calibrated. In some variations, the chamber can be calibrated relative to an individual user, e.g. relative to an individual user's weight.

By controlling the pressure in a chamber of a differential air pressure system with precision, the amount of offloading of the user's weight can correspondingly be controlled with precision. For example, for most individuals, the systems and methods described herein can incrementally change a user's effective body weight by as fine an adjustment as about 1% of the individual's body weight.

In some embodiments, a user seal describes a construction of a soft or flexible material, a stiff or rigid material, or a combination thereof, to span the gap between a user and a chamber in a sufficiently airtight manner. Various non-limiting examples of constructions and methods of accomplishing a user seal are described in U.S. Patent Publication No. 2007/2007/0181121 and U.S. patent application Ser. No. ______, entitled “SYSTEMS, METHODS AND APPARATUS FOR DIFFERENTIAL AIR PRESSURE DEVICES” (Attorney Docket No. 8038.P002) and filed concurrently herewith.

Furthermore, the differential air pressure systems and related methods described herein may be adapted for use used in a variety of different situations, such as, for example, dynamically (e.g., while a user is in motion and not simply standing still) or statically (e.g., while a user is stationary or relatively stationary). In some embodiments, the differential air pressure systems described herein may apply a positive pressure, where the pressure inside the chamber of a differential air pressure system is greater than the ambient pressure of the surroundings. In other embodiments, a negative pressure may be applied to the pressure chamber, the negative pressure being lower than that of the ambient pressure of the surrounding environment.

Determining the gravitational force exerted by a user's body, for example at ground level, may be accomplished using a scale, one or more load cells, one or more pressure sensors, and/or one or more other types of sensors having outputs that may be directly or indirectly calibrated with respect to and/or correlated to load. A measured force may be entered manually into a calibration system in some variations, or may be automatically collected and stored via electronics, which may in some instances be aided by the use of software.

A pressure versus load curve may be constructed for an individual by measuring and recording the force or load experienced by the user as a function of pressure at two or more (pressure, force) data points. Two such (pressure, force) data points determine a linear relationship between load and pressure. However, a linear relationship may become more refined or a nonlinear relationship may be identified and refined by measuring and recording load experienced by the user at more than two pressure points. In some variations, the pressure-load relationship may be refined by increasing the range of pressures over which load is measured.

If desired, a pressure versus load curve can be generated using pre-set or pre-defined pressure points. Such pre defined pressure point(s) can be set in hardware or software for all users, or can be determined by hardware, software, or a combination of hardware and software based on some user metric (such as static weight). For example, a user may enter his body weight at ambient pressure, therefore producing one of the required (pressure, force) data points to begin to construct the pressure-load line or curve. Pressure may be varied discretely or continuously inside a pressure chamber, and a user's weight may be measured at one or more chamber pressures to collect the additional load value(s) to build up the pressure-load curve. In some variations the pressure-load curve may be adjusted and/or scaled based on test data of various subjects. Some non-limiting examples of calibrated systems and related methods that utilize a scale that is capable of making continuous load measurements inside a chamber of a differential air pressure system are described in U.S. Patent Publication No. 2007/0181121, which is hereby incorporated by reference in its entirety, in particular with respect to calibration.

In any of the variations described above or elsewhere herein, a pressure versus load curve may be used as a predictive algorithm (e.g., to predict a pressure at which a user will experience a certain force, or a pressure at which a user will experience a certain degree of unloading, e.g. as a percentage of the user's body weight at ambient pressure or as a force offset by which the user's body weight an ambient pressure is reduced).

Examples of differential air pressure systems are illustrated in FIGS. 1 and 2. FIG. 1 is a block diagram schematically illustrating an example of a differential air pressure system. There, system 100 is configured for applying pressure to a lower body portion 106 of an individual 101 in accordance with one embodiment. The system 100 includes a chamber 102 and a controller 103 for adjusting (increasing or decreasing) the pressure inside the chamber 102. In some variations, the controller 103 may be configured for maintaining the pressure inside the chamber 102. Any suitable controller or controller configuration described herein, now known or later developed can be used to adjust (increase or decrease) the pressure inside the chamber. If the pressure controller 103 is configured to maintain pressure inside the chamber 102, a negative feedback control system may be used in some variations, e.g. as described in U.S. Patent Publication No. 2007/0181121, which is incorporated by reference herein in its entirety.

In the variation illustrated in FIG. 1, the chamber 102 includes an aperture 104 for receiving the lower body portion 106. Although in this particular example aperture 104 is oriented along a vertical axis, in other variations, other locations or orientations of an aperture for receiving a body portion may be used. Any suitable type of shell may be used to form the chamber 102 in the system 100. The chamber 102 may include a soft or flexible shell or a stiff or rigid shell, or a shell that includes a portion formed from a soft or flexible material and a portion formed from a stiff or rigid. material. Some non-limiting examples of suitable shells are described in U.S. Patent Application No. 2007/0181121 and U.S. patent application Ser. No. ______ entitled “SYSTEMS, METHODS AND APPARATUS FOR DIFFERENTIAL AIR PRESSURE DEVICES” (Attorney Docket No. 8038.P002) and filed concurrently herewith, each of which is incorporated by reference herein in its entirety.

In variations in which the chamber 102 has a soft or flexible shell or a shell including a soft or flexible portion and a stiff or rigid portion, the soft shell or soft portion of the shell may be inflated or deflated accordingly. In certain variations, the chamber 102 may occupy an approximately hemi-spherical shape or half-ovoid shape when a soft shell or soft portion of a shell is inflated. FIG. 1 illustrates one embodiment where the chamber 102 includes a top portion of a sphere or ovoid-like shape with a planar cross-section as a base 108 of the chamber 102. The base 108 can supports the individual user 101 in any position, e.g. standing or sitting, such as standing upright or sitting upright. It should be recognized a similar system may be constructed with the user in a horizontal position, e.g. by rotating the aperture 104 by about 90 degrees clockwise or counter-clockwise.

The soft shell or soft shell portion may be made of any suitable flexible material, e.g. a fabric (woven or nonwoven), a thin sheet of plastic, leather (natural or synthetic), and the like. In some variations, the soft shell or soft shell portion may be made from sufficiently airtight fabric that may be woven or non-woven. In some cases, a fabric used in a shell may be slightly permeable to air, but be sufficiently airtight so as to allow a desired degree of pressure to build up in the chamber. While the chamber is deflated, the soft shell or shell portion may allow for the lower body portion 106 to be positioned within the aperture 104. The aperture 104 may include for example an elliptical or circular shape and flexible fabric or other type of flexible material for accommodating various shapes of waistline of the individual lower body 106.

The height of the soft shell or shell portion may be adjusted using a variety of techniques. In one example, a height of a soft shell (e.g. one made from fabric) may be altered by using straps to pull down on the top portion of the shell. In another example, the aperture 104 may include a rigid ring (not shown) that surrounds the waist or torso of the individual 101. The height of the chamber 102 can thus be adjusted by raising or lowering the rigid ring.

One or more bars (not shown) may be provided as part of the system 100 and may be configured to encompass at least a portion of the flexible shell below the waist of the individual 101. Such bar or bars may be configured to hold a flexible portion of shell in along the sides of the chamber to limit expansion, therefore keeping the shell close to the torso of the individual 101 allowing for comfortable arm swing. The bar or bars may limit the ability of a flexible shell from expanding into an undesired shape, e.g. a spherical shape. The bar or bars may have any suitable configuration. For example, in some variations, two parallel bars may be provided along sides. In other variations, one U-shaped bar may be used, where the base of the U-shaped bar may be positioned in front of the user. Similarly, a rigid shell or partially rigid shell may be configured to allow for keeping the arms of the individual 101 from touching or otherwise being interfered with by the rigid shell while the individual 101 is moving (walking or running) through a contoured shape, e.g. a saddle shape. Additional examples of height-adjustable shells and variable shape shells for chambers are described in U.S. Patent Publication 2007/0181121 and in U.S. patent application Ser. No. ______, entitled “SYSTEMS, METHODS AND APPARATUS FOR DIFFERENTIAL AIR PRESSURE DEVICES” (Attorney Docket No. 8038.P002) and filed concurrently herewith, each of which is incorporated by reference herein in its entirety.

The system 100 may also include a rear entrance walkway (not shown) to facilitate entrance and exit to and from the chamber 102. A rear entrance walkway may in some variations include a step. In variations of the chamber 102 having a soft shell or soft shell portion, such a rear entrance walkway, if present, may be used a means for supporting the soft shell or soft shell portion in an deflated state, e.g. so that it is easier to attach a seal 110 to the individual 101. A walkway may also serve as a safety platform in case the shell of the chamber 102 rips (in the case of a flexible shell, e.g. a fabric shell) or breaks (in the case of hard shell). A walkway may also include one or more holding bars for the individual 101 to hold onto to support the individual or to prevent the individual from falling.

With respect to variations of the chamber 102 having a hard shell, the chamber 102 may include a door (not shown) or other type of opening that allows the individual 101 to enter and exit the chamber 102. For example, a door can be used, where the door can swing open, swing down, or slide open. A door can be comprised of fabric, plastic, leather or other type of flexible material that can be closed in a sufficiently airtight manner with a zipper, snaps, and/or other type of closure (e.g. Velcro™ type hook and loop closures). In some variations, aperture 104 may be created by moving two halves of chamber 102 apart and back together like a clam-shell or a cockpit. Additionally, the height of hard shell may be adjusted based on the height of individual 101.

Some variations of adjustable shells for use in differential air pressure systems such as that illustrated in FIG. 1 are described in U.S. patent application Ser. No. ______, entitled “SYSTEMS, METHODS AND APPARATUS FOR DIFFERENTIAL AIR PRESSURE DEVICES” (Attorney Docket No. 8038.P002) and filed concurrently herewith, which is incorporated by reference herein in its entirety.

A seal 110 is provided between the user's lower body 106 and the aperture 104 at or near the torso or the waistline of the individual user 101. In accordance with one embodiment, the seal 110 includes a plurality of openings/leaks around the torso of the individual 101 to cool the individual 101 and/or to better control distribution of pressure around the torso of the individual 101. For example, leaks positioned in front by the stomach of the individual 101 may help with the bloating due to ballooning of a flexible waist seal under pressure. Such deliberate leaks may be implemented by sewing non-airtight fabrics or other materials, or by forming holes in the shell (hard or soft) of the chamber 102. The seal 110 can be made of a substantially airtight material and/or non-airtight material. The seal 110 can be implemented with a skirt, pants (shorts), or a combination of both.

In accordance with one embodiment, the seal 110 may include a separable seal closure. Non-limiting examples of separable seal closures include zippers, snaps, Velcro™ type hook and loop closures, kayak style attachment (e.g. using a zipper) over a rigid lip that is attached to the shell, clamps, and deformable loops. In some variations, the seal 110 may include means for anchoring to the individual lower body 106 and means for attaching to the aperture 104. Means for anchoring to the user's body may include, for example, Velcro™ type straps that extend around the circumference of a user's thighs for adjustment to accommodate different thigh sizes, and a belt that keeps the seal anchored at the hipbone. Other examples of means for anchoring to the user's body may include a high friction material that seals against the user's body and remains anchored because of a high friction coefficient. The seal 110 may be breathable and washable. In accordance with another embodiment, the seal 110 may seal up to the individual chest, and in some variations the seal may extend from the user's waist region up to the chest. In some variations, the seal 110 may include a skirt-type seal. Additional non-limiting examples of seals are described in U.S. Patent Publication No. 2007/0181121 and U.S. patent application Ser. No. ______, entitled “SYSTEMS, METHODS AND APPARATUS FOR DIFFERENTIAL AIR PRESSURE DEVICES” (Attorney Docket No. 8038.P002) and filed concurrently herewith, each of which is incorporated by reference in its entirety.

An optional exercise machine 112 may be at least partially housed within the chamber 102. Any suitable exercise machine may be used, e.g. a treadmill, a stationary bicycle, a rowing machine, a stepper machine, an elliptical trainer, a balance board, and the like. The exercise machine 112 may be, for example, a treadmill having an adjustable height, inclination, and speed. Any parameter of the exercise machine can be adjusted based on a dimension of the individual user 101. For example, the height, position within the chamber, seat position, handgrip position, and the like, of the exercise machine 112 can be adjusted to accommodate a dimension of the individual 101. Those of ordinary skill in the art will appreciate that the treadmill shown is not intended to be limiting and that other exercise machines can be used without departing from the inventive concepts herein disclosed.

In some variations, a differential air pressure system includes a pressurizable chamber without an exercise machine 112. In these variations, the chamber 102 may be used without any exercise machines, e.g. as a means to improve jumping ability, balance, or general movement.

Any suitable type of controller 103 can be used for adjusting the pressure inside the chamber 102. As stated above, the controller 103 in some variations is configured to maintain the pressure in the chamber 102, e.g. if the controller 103 is configured as a negative feedback control system. In certain variations, the controller 103 includes an intake system 114 and an outtake system 116. In some cases, the controller 103 may include a pressure sensor 120, a processor 122, or a control panel 118, or any combination of two or more of the above.

In the variation illustrated in FIG. 1, intake system 114 includes an input port 124 for receiving a gas (for example, air), a pressure source 126 (pump or blower), and an output port 128. The gas flow from pressure source 126 may be unregulated. Pressure source 126 can be turned on or off. In accordance with another embodiment, the pressure source 126 may include a variable fan speed that can be adjusted for controlling the incoming airflow to the chamber 102. Pressure source 126 pumps gas from input port 124 to output port 128.

In the variation illustrated in FIG. 1, outtake system 116 includes an input port 130 for receiving gas from chamber 102, a pressure regulating valve 132, and an output port 134 to ambient pressure. The pressure regulating valve 132 controls the exhaust flow from the chamber 102. The input port 130 is an output port of the chamber 102. Gas leaves the chamber 102 via the output port 134. In accordance with another embodiment, a safety exhaust port (not shown) may be connected to the chamber 102 for allowing gas to exit the chamber 102 in case of pressure increasing beyond a limit such as a safety limit, e.g. in an emergency or a system failure.

In some variations, the differential air pressure system as illustrated in FIG. 1 includes a user interface system for allowing the individual 101 or an operator to interact with the system 100 via the processor 122. Any suitable user interface may be used, e.g. a touch sensor such as a touch screen, a handheld button, a handheld control box, or a voice-activated user interface. In certain variations, a control panel 118 includes a user interface system. The user interface and/or the control panel may be interfaced with the processor 122 in a wireless configuration or hardwired. In some variations, the individual 101 may use a touch-screen interface (not shown) on the control panel 118, e.g. to program the pressure within the chamber 102, and/or to control one or parameters of the exercise machine, e.g. the speed, the inclination, the resistance and/or the height of the exercise machine 112. The control panel 118 may also be used by the individual 101 to calibrate the system for correct body weight and/or to input a desired factor or parameter to determine an intensity of exercise. For example, the user may specify that he wants to exercise at a certain fraction of his body weight, or offset his body weight by a certain number of pounds, or exercise at a certain heart rate or blood pressure, or exercise at a certain pain level. Non-limiting examples of calibration processes are described in further detail below.

In one embodiment, an optional pressure sensor 120 is connected to the chamber 102 for measuring a differential pressure between the pressure inside the chamber 102 and the ambient pressure. Those of ordinary skill in the art will appreciate that the pressure sensor 120 shown is not intended to be limiting and that other types of pressure transducer or pressure measuring sensors can be used without departing from the inventive concepts herein disclosed. The pressure sensor 120 communicates its measurements to the processor 122. As described herein, system 100 does not need to include pressure sensor to accomplish the calibration process as described in the some of the variations of methods and systems below.

In some variations, the controller 103 can be configured to use input from the pressure sensor 120 to control the pressure source 126 and/or the pressure regulating valve 132. The processor 122 can communicate with the user interface or control panel 118, if present. An example of the algorithm of the processor 122 is the processor 122 receives an input from the control panel 118. For example, the input may include a desired pressure within the chamber 102, a desired percentage of body weight of the individual, an amount of weight to offset the user's body weight, and/or a pain level. The processor 122 can be configured to operate the pressure source 126 and/or the regulated valve 132 using a negative feedback loop, circuit, or system. The processor 122 can in certain variations monitor the pressure inside the chamber 102 with input from the pressure sensor 120. Based on the measurements from the pressure sensor 120 and the input from user, e.g. via the control panel 118, the processor 122 sends a drive signal to the regulated valve 132 and/or the pressure source 126 to increase or decrease the exhaust flow through the chamber 102 so as to maintain the pressure within chamber 102 as close as possible to the desired pressure. The desired pressure may be pre-set in some variations, and in some variations may be received from the control panel 118 or derived from information received from user, e.g. via the control panel. The pressure (positive or negative) inside the chamber 102 produces an upward or downward force on the individual 101 resulting in a lighter or heavier sensation.

The processor 122 may in some variations communicate with the exercise machine 112. The processor 122 may receive one or more input parameters via the control panel 118 for the exercise machine 112. For example, the exercise machine 112 may include a treadmill with speed or inclination adjusted by the processor 122 based on the pressure sensed inside the chamber 102.

In accordance with some embodiments, the system 100 may be controlled to monitor and/or maintain various performance parameters, such as to achieve a constant stride frequency. In some variations, the processor 122 may be configured to receive input from one or more user performance parameter sensors, e.g. heart rate, blood pressure, pain level, stride length, cadence or stride frequency, foot strike pressure, and the like. One or more parameters of the exercise machine such as speed, resistance and/or pressure inside the chamber may be adjusted in response to the one or more user parameters. For example, a sensor may be placed on a treadmill to detect the impact from the user's feet on the treadmill and compare with subsequent values to measure the time duration between strides. The machine can then adjust pressure, tilt, speed, etc. to maintain a specific stride rate.

In accordance with yet another embodiment, the system 100 may include an acceleration/deceleration sensor coupled to the individual 101 sensing whether the user is speeding up or slowing down. Those of ordinary skill in the art will recognize that there are many ways of implementing such a sensor. The processor 122 receives the measurement from the acceleration/deceleration sensor and may send a signal to increase or decrease the speed of the treadmill in response to the measurement in combination with increasing or decreasing the pressure inside the chamber 102.

The processor 122 may also include a data storage (not shown) such as a database storing various data and/or executable programs that may be selected or programmed in by the individual 101 or by an operator via the control panel 118. The data storage may include a repository of data that may be used to control the system 100. For example, while receiving data from one or more sensors (including the pressure sensor, performance sensors of the individual, a safety sensor, etc. . . . ) the processor 122 may determine that one or more parameters has reached a pre-set limit or a dangerous level. The processor 122 then alters the pressure and/or a parameter of the exercise machine 112, e.g. a resistance or speed, e.g. the speed of the treadmill. For example, a trainer could set a maximum speed, heart rate, resistance, cadence, blood pressure, or pain parameter for the individual 101. The processor 122 would ensure that that parameter is not to be exceeded. The data storage may also be used to store past performance data and personal records for different protocols and the system 100 could allow the individual 101 to run against previous performance data or personal records.

The data storage may also include various training programs based on the selection from the control panel 118. The processor 122 could then limit activity levels to non-harmful ranges for the individual 101 based on one variable, a combination of variable, or all variables. The data storage may also be able to log and record the performance and activities of the individual 101 as well as store any calibration data so that the individual 101 trainer, therapist or the like need not perform that the calibration process for every use of the differential air pressure system.

FIG. 2 is a block diagram schematically illustrating a system 200 for applying pressure to a lower body portion 106 the individual 101 in accordance with another embodiment. The system 200 includes the chamber 102 and controller 202 for adjusting (increasing or decreasing) the pressure inside the chamber 102. In some variations controller 202 can be configured to maintain pressure inside the chamber 102. An example of controller 202 is a negative feedback control system.

Controller 202 for adjusting (and in some variations maintaining) the pressure inside the chamber 102 includes an intake system 204. In some variations, the controller includes a user interface such as described in connection with FIG. 1. In certain variations, a user interface may be included as part of a control panel 118. In some variations, controller 202 includes a pressure sensor 120, and a processor 206.

In the variation illustrated in FIG. 2, the intake system 204 includes an input port 208 for receiving a gas (for example, air), a regulated pressure source 210, and an output port 212. The regulated pressure source 210 pumps gas from the input port 208 to the output port 212. The output port 212 is also an input port into the chamber 102. Gas is pumped in and out of the chamber 102 via the output port 212. The inflow of air is regulated via the regulated pressure source 210. The regulated pressure source 210 includes an adjustable exhaust valve for controlling the gas flow rate through output port 212. In accordance with some variations, the regulated pressure source may include a pump having an adjustable fan blade size or fan speed. The gas flow rate can be adjusted by varying the fan speed or fan blade size. A safety exhaust port (not shown) may be connected to the chamber 102 for allowing gas to exit the chamber 102 in case of a pre-set limit is reached, e.g. in an emergency or a system failure.

The processor 206 communicates with the control panel 118, if present, and the pressure sensor 120 to control the regulated pressure source 210. An example of the algorithm of processor 122 is the processor 206 receives an input from the user, e.g. via control panel 118. For example, the input may include a desired pressure inside the chamber 102, a body weight of the individual, a factor to determine a percentage of body weight that the individual would like to experience during exercise, a weight offset the user would like use to offset his weight at relative to weight at ambient pressure, a pain limit, a heart rate, and/or a blood pressure, and the like. In the variation illustrated in FIG. 2, the processor 206 can operate the regulated pressure source 210 using a negative feedback loop, circuit, or system. The processor 206 monitors the pressure inside the chamber 102 with the pressure sensor 120. Based on the measurements from the pressure sensor 120 and the input from the user (e.g. via control panel 118), the processor 122 sends a drive signal to the regulated pressure source 210 to increase or decrease the gas flow through the chamber 102 so as to maintain the pressure within chamber 102 as close as possible to the desired pressure received from the user, e.g. via control panel 118. The pressure (positive or negative) inside the chamber 102 produces an upward or downward force on the individual 101 resulting in a lighter or heavier sensation.

In some variations, the processor 206 may communicate with an exercise machine 112 at least partially housed inside the chamber 102. Any suitable exercise machine 112 may be used, e.g. as described above in connection with FIG. 1. In some variations, no exercise machine is used. The processor 206 may receive one or more input parameters (e.g. speed, resistance, cadence, incline, workout algorithm, or the like) from the user, e.g. via control panel 118, for the exercise machine 112. For example, the exercise machine 112 may include a treadmill with speed or incline adjusted by the processor 206 based on the pressure sensed inside the chamber 102.

The processor 206 may also include a data storage (not shown) such as a database storing various data and/or executable programs that may be selected or programmed in by the individual 101 or an operator via the control panel 118. The data storage may include a repository of data that may be used to control the system 200. For example, while receiving data from all sensors, the processor 206 may determine that one or more parameters have reached a pre-set limit or a dangerous level. The processor 206 then alters the pressure and/or one or more parameters of the exercise machine 112, e.g. the speed of a treadmill. For example, a trainer or physical therapist could set a maximum speed parameter for the individual 101. The processor 206 could limit that speed so that it is not exceeded. The data storage may be used to store past performance data and/or personal records for different protocols and the system 200 could allow the individual 101 to train against previous performance data or personal records.

The data storage may also include various training programs based on a selection from the control panel 118. The processor 206 can in some variations limit one or more activity levels of the individual to non-harmful levels based on one or more variable, e.g. based all the variables. The data storage may also be able to log and record the performance and activities of individual 101.

In one embodiment, methods for calibrating a differential air pressure system, e.g. as illustrated in FIG. 1 or 2, comprise adjusting pressure in the chamber until force experienced by the user reaches a target force value, and measuring the pressure at which the target force value is reached to obtain a first (pressure, force) data point, where the force value is the target force value and the pressure is the chamber pressure measured when that target force value is reached. The methods may in some variations comprise using the first (pressure, force) data point to determine (e.g. by extrapolation and/or interpolation) a relationship between body weight force experienced by the user and chamber pressure. An example of such a process variation is illustrated in FIG. 3.

The process variation illustrated in FIG. 3 does not require a scale or other device that is capable of continuous load measurement be placed inside the pressure chamber to enable a person's weight be measured as a function of pressure. Instead, a force such as a user's body weight can be sensed inside the chamber, and a pressure at which the force reaches a preset force level can be determined. For example, the system may include a platform or surface against which the user exerts body weight force. A pressure at which the user's body weight reaches a target force value (i.e. a known weight which may in some variations be predetermined) can be measured to generate a first (pressure, force) data point, where the force is the target force value and the pressure is the differential chamber pressure measured at the target force value. The comparison between the force on the user and the target force value or known weight can be accomplished using any suitable mechanism or setup, e.g. by use of a simple balance or counterweight configuration. The first (pressure, force) data point can then be used in combination with at least one more (pressure, force) data point to generate a pressure-load curve for the system. In some variations, a user's body weight at ambient pressure can be used as one of the additional (pressure, load) data points. One or more additional (pressure, load) data points can be obtained by measuring one or more additional pressures at which the user's body weight in the pressure chamber reaches one or more other target force values. At least one of the target force values used in the calibration process can be preset in some variations, e.g. preset as to all users of a differential air pressure system. In other variations, one or more of the target force values can be determined or selected by the system for a particular individual. For example, a system may select a larger target force value based in input from a user indicating a relatively high normal body weight, and a smaller target force value based on input for a user indicating a relatively low normal body weight. The (pressure, load) data points so gathered can be used to generate a pressure-load curve. In some variations the pressure-load curve may be adjusted and/or scaled based on test data of various subjects. Pressure-load data points may for example be obtained for a set of subjects using a differential air pressure system equipped with scales or load cells in the pressure chamber, and a pressure sensor coupled to the chamber.

Referring now to FIG. 3, such a calibration process begins by processing logic adjusting pressure in a pressure chamber that is sealed around at least a portion of a user's body until an initial force or load target value is reached, and measuring the pressure (or a parameter that can be related to pressure such as exhaust valve position or power draw by a pressure source, as is described herein) at which the force or load target value is reached (processing block 302). The process may be performed by processing logic that may comprise hardware (circuitry, dedicated logic, etc.), software (such as is run on a general purpose computer system or a dedicated machine), or a combination of both hardware and software. In some variations, processing logic resides in processor 122 of FIG. 1 or processor 206 of FIG. 2. The force or load against which the system is calibrated can be a force exerted on a surface, or other sensing point, of the system. A surface against which a force is exerted may be in any orientation relative to the system.

In some variations, a measurement of force experienced by the user can be obtained from the user's body weight on a surface at the base of the system. In some variations, the force measurement is obtained from an upper surface, such as, for example, a hanging load measurement device. For example, FIG. 9 provides an illustration of one variation of a differential air pressure system 900 comprises a hanging load measurement device 901. There, the device 901 comprises one or more force sensors 902 (e.g. one or more springs, tension gauges, and the like) attached to a user 904 that has at least a portion of his body enclosed in a chamber 906 of the differential air pressure system 900. The difference between P₁ (pressure inside the chamber) and P₂ (pressure outside the chamber) alters force experienced by the user 904. The pressure P₁ inside the chamber 906 can be increased until the force experienced by the user reaches a target force F₁, as sensed by the one or more force sensors 902. As described above, an initial load value may be the full user body weight measured and entered at ambient pressure in the system. The entering of the data may be done by the user or measured by the system with no pressure differential in the chamber (i.e. at ambient pressure).

A second target force value is then set and the corresponding system pressure (or a parameter that can be related to pressure such as exhaust valve position or power draw by a pressure source, as is described herein) is recorded when the force sensed (e.g. the user's body weight) reaches the target force value (processing block 304). Step 304 may be repeated as many times as desired. In some variations, the target force value or values can be set in hardware and/or software for all users. In certain variations, the predetermined force targets values are determined by hardware, software, or a combination of hardware and software based on a user metric (such as static full body weight at ambient pressure). For example, the force targets may be created based on a percentage of the static weight of the user at ambient pressure. In some variations, the pressure is varied in the system of FIG. 1 or FIG. 2 by processing logic until a force/load exerted by a user's body on a surface of the system is effectively equal to, just greater than, or just less than a pre-set force value.

A correlation can then be computed using the two or more (pressure, load) data points (processing block 306) (i.e. a load-pressure curve is generated). In some variations the pressure-load curve may be adjusted and/or scaled based on test data of various subjects. In some embodiments, the correlation allows the system to create a predictive pressure vs. load curve to adjust a user's effective body weight in the chamber by adjusting the pressure in the chamber.

In some variations, processing logic returns to processing block 302 to repeat the sense and calibration process 300. In some variations, the processing logic may return to processing block 302 after completing processing block 304 to gather more (pressure, load) data points prior to calculating a correlation of pressure and body weight (processing block 306). The calibration process may be optionally repeated for several other target force values, for establishment of additional pressure values, e.g. a broader or narrower range of pressure values, or to enable a more accurate correlation between force and pressure to be created. For example, multiple (pressure, load) data points may be desirable in certain circumstances because of the non-linearity of the system at lower body weights.

Because force is utilized as a control variable, while pressure is adjusted until measured force meets force target values, the process of FIG. 3 may be extended to systems and methods where target load values (which may be preset) are measured via springs, deformable elastic materials, or other known force application schemes as described herein, known in the art, or later developed.

As discussed earlier, variations of systems and methods that adjust pressure until sensed force reaches one or more target force values and measuring the pressure (or a parameter that can be related to pressure such as exhaust valve position or power draw by a pressure source, as is described herein) associated with the one or more target force values may be advantageous in certain circumstances. For example, such systems and methods may use a force sensing means that need not quantify force, e.g., it may not be necessary to read continuous force values. Instead, such systems need only be capable of sensing force relative to a target force value, e.g. with a balance, spring, counterweight, elastic, and the like. The result may be a system with reduced electrical and/or mechanical complexity thereby increasing reliability of the system while reducing system cost.

FIG. 4 is a flow diagram 400 schematically illustrating another example of a method for calibrating a differential air pressure system, e.g. a system illustrated in FIG. 1 or FIG. 2. The process can be performed by processing logic that may comprise hardware (circuitry, dedicated logic, etc.) software (such as is run on a general purpose computer system or a dedicated machine), or a combination of both hardware and software. In some embodiments, processing logic resides in processor 122 of FIG. 1 or processor 206 of FIG. 2.

Referring to FIG. 4, the process begins with a force/load exerted by the user on a spring or compliant surface with which the load is subsequently sensed or measured (processing block 402). The compliant surface or spring may be used to sense or measure force/load at ambient pressure or at a system pressure. In one embodiment, the force is measured as deformation of a board, which may for example comprise two platforms, where the platforms are separated by a spring or spring-like material.

Any system or method where deflection is measured to indicate or correlate with applied user load shall be considered within the scope of this invention. In some variations, when a spring deforms (e.g., when a user exerts a force on the spring such as by standing on the platforms), the spring deflection may be measured and correlated with applied user load. In some variations, one or more sensors, for example one or more capacitance meters or sensors, may be placed along the deforming axis of the spring to obtain a deflection measurement, which can then be correlated to load via a known compliance of the spring and output of the sensor, e.g. capacitance to indicate a distance between two plates. Any suitable type of sensor to sense deflection may be used, e.g. displacement sensor(s), optical sensor(s), or Hall effect magnet sensor(s).

It should be noted that in the method variations described and illustrated in connection with FIG. 4, deflection can be measured by a suitable sensor quantitatively in a continuous manner, or deflection can be sensed or measured as relative to a reference value; for instance, a spring may be preset to unload to a known force value and a switch (e.g. binary switch) may alert a processor when that degree of reduction of force has been achieved. In some variations, a certain degree of loading may be known from a certain amount of deflection, because the sensors may be preset to known load values that are correlated by the compliance of the spring or board the sensor is coupled to. In another example, two switches may be set, and the pressure may be varied until the first switch is triggered, and pressure may be adjusted until the other switch is triggered. By knowing the difference in force required to trigger each switch and the pressures at which each switch was triggered, an appropriate pressure-load curve or correlation can be obtained. In certain variations, the system may contain multiple ones of such trigger switches.

In some variations, a (pressure, load) data point obtained at ambient pressure/full body weight may be entered by the user or by the system and used in combination with one additional (pressure, load) data point obtained by measuring deflection of a board or spring of a user in the chamber at a single pressure to construct a simple linear pressure-load relationship. In some variations, multiple sensors may be used to measure deflection of the board, spring or compliant surface, and the data from the multiple sensors recorded for a more accurate construction of a force/load versus pressure curve.

After the first data point is obtained, the pressure in the chamber can be varied until a target force value is reached (processing block 404). In this particular variation, the target force value is in the form of a known deflection based on the compliance of the system. Once the target deflection is achieved, the pressure value (or a value that can be linked to pressure, such as an exhaust valve setting or power draw by a pressure source, as described herein) is measured. This process may in some variations be repeated multiple times to obtain multiple data points. The repetition of the process may occur after processing block 404, as shown with a dashed line in FIG. 4, or after processing block 406.

A correlation between the chamber pressure and body weight force as measured by the deflection is created (processing block 406). In one embodiment, the correlation allows the system to create a predictive pressure vs. load curve to adjust a user's effective body weight in the chamber by adjusting the pressure in the chamber. In certain variations, multiple deflection measurements of a board or spring or other compliant surface may be obtained at multiple pressures to generate more (load, pressure) data points, which may in turn lead to a more accurate linear or nonlinear pressure-load curve. In some variations the pressure-load curve may be adjusted and/or scaled based on test data of various subjects.

FIG. 5 is a flow diagram 500 schematically illustrating another example of a method for calibrating a differential pressure system, e.g. the systems illustrated FIG. 1 or FIG. 2. The process can be performed by processing logic that may comprise hardware (circuitry, dedicated logic, etc.), software (such as is run on a general purpose computer system or a dedicated machine), or a combination of both. In one embodiment, processing logic resides in processor 122 of FIG. 1 or processor 206 of FIG. 2.

Referring to FIG. 5, the process begins by processing logic receiving data indicating the system is at zero differential pressure (ambient pressure) (processing block 502). In one embodiment, the data may be received from the user, e.g. via control panel 118, a scale and/or switch (e.g. a pressure sensitive switch that can detect to a desired degree of accuracy when a weight is pressing down on the switch) coupled with the system, or if the system has the pressure source turned off and therefore knows there is no pressure being applied in the system, etc.

Pressure can then adjusted in the system until no user body weight is detected on a scale or switch (processing block 504). In one embodiment, a lift-off pressure in the chamber corresponds to the pressure at which the user is sufficiently separated from the measuring surface, or a sufficiently low force is exerted by the user on the measuring surface so that reasonable accuracy is obtained when assuming this pressure measurement value corresponds to an effective zero user weight. Any suitable sensor or sensor type may be used to detect when the user exerts no detectable force on the measuring surface, e.g. a weight sensor, or a displacement sensor or other type of sensor to detect a separation between the user and a surface of the system such as an optical sensor, Hall effect magnetic sensor, resistive sensor, capacitive sensor, or the like. In another embodiment, data received from a user, e.g. by a control panel or handheld user control interface to send a signal to alert processing logic that the user has been lifted off of the surface (e.g., for example, a user pressing a button to halt the increase in pressure).

A correlation between pressure and force (which can be expressed as a percent of a user's body weight) is then created (processing block 506). As discussed in connection with other embodiments describe herein, the correlation allows the system to create a predictive pressure vs. load curve to adjust a user's effective body weight by adjusting the pressure in the chamber. The curve may be assumed to be a straight line with two (pressure, load) data points used as end pressure and load intercept points, or the curve may assume a non-linear relationship. In some variations the pressure-load curve may be adjusted and/or scaled based on test data of various subjects.

As discussed with reference to FIG. 5, the first (pressure, load) data point used can be at zero differential pressure and 100% effective body weight measured at ambient pressure, and the second (pressure, load) data point can be at a full pressure measurement at which 0% effective body weight value is sensed.

The processing logic can be supplied with at least two (pressure, load) data points to construct pressure-load relationship (e.g. a line in the case that two pressure-load data points are supplied). The logic can then calibrate the system, e.g. relative to the body weight of the user at ambient pressure, such as a percentage of the ambient pressure body weight, or as an offset from the ambient pressure user body weight. For example, a user may enter his body weight to give an estimate of absolute effective body weight, not just an effective percent body weight, and the system may operate in terms of absolute weight units, not just relative body weight units, e.g. percent body weight.

FIG. 6 is a flow diagram 600 schematically illustrating another example of a method for calibrating a differential pressure system, e.g. as illustrated in FIG. 1 or FIG. 2. The process can be performed by processing logic that may comprise hardware (circuitry, dedicated logic, etc.), software (such as is run on a general purpose computer system or a dedicated machine), or a combination of both. In one embodiment, processing logic resides in processor 122 of FIG. 1 or processor 206 of FIG. 2.

Referring to FIG. 6, the process begins by processing logic receiving data indicating a user's body weight at ambient pressure (processing block 602). In one embodiment, the weight is received when a user steps on a scale coupled with processing logic, from a control panel, etc. In another embodiment the weight is simply entered by the user as his known body weight at zero system pressure. In another embodiment the process begins with processing 604, and requires at least one repetition of the processing blocks 604 and 606 to collect at least two (pressure, load) data points required to form a pressure vs. applied load curve for the user.

The force exerted by the user on a surface of the system relative to one or more objects of known weight is measured (processing block 604). Processing logic then adjusts system pressure until the force exerted by the user equals the known weight(s) (processing block 606). In one embodiment, pressure is adjusted until force exerted by the user equals the known weight(s) of the object within some reasonable tolerance. Processing logic may optionally repeat processing blocks 604 and 606 multiple times.

In the embodiment discussed in FIG. 6, calibration is enabled by a form of scale system. An example of such a scale system may be a beam that the user stands on that pivots at a point between the user and the object of known weight. The user is then unloaded (e.g., pressure is adjusted) until the force or torque applied by the user and the object cancel. At this point, the user is known to weigh some ratio of the weighted object by taking into account the relative distances from the pivot and the mass of the beam. An example of a scale system is illustrated in FIG. 10. There a differential air pressure system 1000 includes a chamber 1002, with at least a portion of body of the user 1004 surrounded by the chamber 1002. The differential air pressure system 1000 comprises a scale system 1010. The scale system 1010 comprises a platform 1012 that supports the user 1004. The platform 1012 is coupled to one end 1014 of a beam 1016. A spring 1024 with a known spring constant k_(s) connects an end 1020 of beam 1016 that is opposite end 1014 (that supports the user) to the ground or other reference point. The beam 1016 is balanced on a pivot block 1018 at pivot point 1022. One or more sensors 1026 are placed on the beam 1016. The sensor(s) 1026 may be any suitable type of sensor (e.g. a tilt sensor, a torque sensor, and the like). As the user exerts force on the end 1014 of the beam 1016, the beam pivots at pivot point 1022, causing a spring 1024 to compress or expand. Pressure P₁ in the chamber 1002 may be adjusted until the force exerted by the user on the beam 1016 causes the beam to balance out the force due to the spring 1024. In certain variations, any one of the spring constant k_(s) of the spring 1024 may be changed, the length of the beam 1016 may be changed, and the position of the pivot point 1022 along the beam 1016 may be changed. The weight of the user may be measured in the manner using multiple objects having known weights and the associated pressure values stored to create the pressure versus load curve for that individual. Furthermore, as discussed herein, a user may also enter his normal body weight at zero system pressure as one valid (pressure, load) data-point to be used in the creation of a prediction curve.

In some variations a differential air pressure system, e.g. as illustrated in FIG. 1 or FIG. 2, may be calibrated by user pain level relative to pressure. Such calibration using pain may be performed instead of or in addition to calibrating effective body weight relative to pressure. FIG. 7 is a flow diagram 700 schematically illustrating an example of a method for calibrating a differential air pressure system by the use of user pain level relative to pressure. The process can be performed by processing logic that may comprise hardware (circuitry, dedicated logic, etc.), software (such as is run on a general purpose computer system or a dedicated machine), or a combination of both. In one embodiment, processing logic resides in processor 122 of FIG. 1 or processor 206 of FIG. 2.

Referring to FIG. 7, the process begins by processing logic adjusting system pressure (processing block 702). In one embodiment, system pressure of the bag is increased to a predetermined initial or threshold level, and then adjusted according to user pain as discussed below. In another embodiment, system pressure is increased from zero system pressure rather than from a predetermined initial or threshold level.

Data is received that indicates a user's current pain level (processing block 704). In one embodiment, as the pressure in the bag is increased, a user can input how much pain they feel. The user may answer questions, turn a dial on a control panel 118, press a button of control panel 118 to determine a threshold or level of pain (e.g. a user may select a button to indicate a level on a pain scale, which may for example be a pain scale from 0 indicating no pain to 10 indicating intolerable pain), respond to prompts supplied by the system (e.g. by pressing a number on a number pad, verbally, or any kind of touch sensor, or use any other known method of user input). In one embodiment, this pain measurement can be taken either statically or dynamically, meaning the user can be standing still or in motion. Steps 702 and 704 in the process 700 may be repeated until a level of pain indicted on a pain scale and/or a maximum pain threshold is determined to be appropriate for the user. The process may be halted by any signal from the user if pain is too great.

Pressure is then correlated with the data indicating user pain level relative to pressure (processing block 706). In one embodiment, the system correlates pressure with pain to enable the system to automatically adjust pressure to allow a user to move based on comfort level. Furthermore, the correlation may enable the pressure differential system, e.g. as illustrated in FIG. 1 or FIG. 2, to adjust one or more workout metrics, such as speed of a treadmill, incline, resistance, pressure regulation, pressure level, etc., to adjust the workout based on known user pain tolerances.

In certain variations of differential air pressure systems, such as those described in connection with FIG. 1 or FIG. 2, pressure in the chamber can be controlled by controlling flow of gas into and/or out of the pressure chamber, i.e. using an air intake valve to control flow into the pressure chamber, air exhaust valve to control flow out of the pressure chamber, or a combination thereof. Thus, by knowing how gas flow into and/or out of the chamber affects pressure, pressure in the chamber can be determined without a direct pressure measurement.

In certain variations of differential air pressure systems, such as those described in connection with FIG. 1 or FIG. 2, load experienced by a user in a pressure chamber can be determined without measuring the individual's weight. For example, where pressure chamber contains an active exercise system, such as a treadmill, the startup power in a motor could be used to determine effective user body weight, rather than via user input or a scale coupled with differential air pressure system. Without any load, a motor consumes a certain amount of power to start the exercise system. When a user is impeding starting of the motor, such as by standing on the belt of a treadmill or by having their legs on a bike, the amount of power it takes to start the system increases.

Thus, one or more system resources other than measured chamber pressure and can be utilized for calibrating a system to determine user load. For example, by controlling gas intake, exhaust flow, or some combination of thereof, a correlation can be found between pressure and the expenditure of that resource. Power (voltage or current) consumed by the pressure source (e.g. blower) may be correlated to pressure in a chamber. In some variations, position of an exhaust valve may be correlated to chamber pressure. In some variations, a startup power (voltage and/or current) needed to operate an exercise machine (such as a treadmill, elliptical trainer, or stepper) may be correlated with user applied load (which incorporates user's body weight). Such data from system components or devices that is other than pressure in the chamber or a direct or indirect measure of a user's body weight but that can be linked to pressure or load can be used to generate a set of (pressure, load) data points with which to calibrate a differential pressure system. The calibration curve may be generated using these system device parameters other than pressure or load as appropriate. For example, the chamber pressure may be calibrated versus startup power needed to operate an exercise machine, or load in the chamber (e.g. as a percentage of user's ambient pressure body weight) may be calibrated versus exhaust valve position or power delivered to a pressure source. In some variations, startup power needed to operate an exercise machine may be calibrated versus a valve position or power delivered to a pressure source.

FIG. 8 is a flow diagram 800 schematically illustrating an example of a method for calibrating a differential air pressure system, e.g. as illustrated in FIG. 1 and FIG. 2. The process can be performed by processing logic that may comprise hardware (circuitry, dedicated logic, etc.), software (such as is run on a general purpose computer system or a dedicated machine), or a combination of both hardware and software. In some embodiments, processing logic resides in processor 122 of FIG. 1 or processor 206 of FIG. 2.

As discussed above, in some variations, the system device used to calibrate a differential air pressure system may be a motor of an exercise machine such as a treadmill motor, an elliptical trainer motor, or a stepper machine motor, an exhaust valve position that controls air exhaust from the chamber, or input blower control power (voltage or current), etc. While the device(s) are adjusted, pressure or load is monitored directly or indirectly as appropriate.

As discussed above, chamber pressure can be a known function of a system device parameter, e.g. exhaust valve position or power consumed by the pressure source (blower). For example, chamber pressure can be automatically or manually correlated with exhaust valve position or power consumed by the pressure source. Such a correlation can, for example, be established during a system design stage, or an initial setup stage. Further, load can be a known function of a system device parameter, e.g. startup power of an exercise machine. For example, startup power of an exercise machine can be automatically or manually monitored as a function of user applied load, e.g. during system design or as an initial setup stage. If the correlation of chamber pressure or load with a system device parameter is accomplished automatically processing logic can control adjustment of the system device parameter and monitor pressure chamber or user applied load in response.

In some variations, it may not be necessary to determine a continuous relationship between the device system parameter and pressure or load. For example, it may be sufficient to know the relationship between a device system parameter and pressure or load at a single point, e.g. exhaust valve position or power consumption by a pressure source can be determined for a single chamber pressure. Startup power by an exercise machine can be determined at a single user load value.

Once it is known how a system device parameter correlates with pressure or load at one or more points, the differential air pressure system can be calibrated using that system device parameter. One example of such a process is illustrated in flow chart form in FIG. 8. There, the process begins by adjusting one or more devices of a system, where a parameter of that device has been correlated with pressure or load (processing block 802). In the variation illustrated in FIG. 8, the device parameter can be adjusted until it reaches a value corresponding to a known pressure or load value (processing block 804). The user data in terms of pressure, load or a related quantity can be determined from the known monitored values (processing block 806). The process steps 804 and 806 may be repeated as many times as desired, as indicated by the dashed lines.

By using processing logic to monitor startup energy, power, voltage, amperage, inertia, torque, or any combination of these at different levels of applied load, processing logic may determine the change in the user's effective body weight while one or more of the system devices are adjusted. For example, a differential air pressure system using the method illustrated in FIG. 8 may set an initial target startup current value and adjust chamber pressure until the target value is reached. The system may repeat this process multiple times, storing both the pressure and the target value each time. The system may then use a known correlation between startup current and load in conjunction with the measured pressures to create a pressure vs. effective body weight curve for the user. It should be clear that startup current is but one example, and other system device parameters may be used in the methods described above, e.g. in connection with FIG. 8.

In another embodiment, where the system device parameter is a system exhaust, an exhaust valve position versus chamber pressure can be pre-calibrated for the system. The system can determine one or more opening sizes of the exhaust valve, or one or more valve positions to adjust pressure in the chamber to reach one or more preset loads. Because the pressure versus load curve may be determined and used as a predictive function of exhaust valve position and effective body weight, eliminating the need for a pressure sensor.

In yet another embodiment, where the control is a system input blower control voltage or current, the voltage or current to the blower can be changed by processing logic to find a voltage or current to adjust pressure in the chamber to reach one or more preset loads. Therefore, voltage or current draw by the blower can be calibrated to effective body weight curve in a similar manner. Here again, the calibration process utilizes flow rate of gas into pressure chamber of the system to control pressure, and utilizes a known system conversion between blower power consumption and pressure, but does not require a direct measurement of pressure.

While embodiments and applications of this invention have been shown and described, it would be apparent to those skilled in the art having the benefit of this disclosure that many more modifications than mentioned above are possible without departing from the inventive concepts herein. For example, the present invention may be applicable to containing any part of the body, such as the upper body, torso area, etc. The invention, therefore, is not to be restricted except in the spirit of the appended claims. Furthermore, embodiments of the systems, apparatuses, and methods described herein may be practiced individually, or in combination. Many different combinations would be apparent to those skilled in the art having the benefit of this disclosure.

It shall be understood that any of the concepts described herein may be joined together, or combined, to form a useful invention. For example, any combination of the calibration and sensing methods described herein may be implemented to accomplish a system that performs calibration. For the sake of brevity, and to avoid obscuring the individual concepts discussed above, not all combinations of the inventions described herein have been listed, but combinations shall be held within the scope of this patent. Additionally, it shall be understood that systems that described a pressurized chamber may be construed to include both positive and negative pressure configurations. Positive verses negative pressure may require different configurations of the inventions but such modifications from those explicitly described herein shall be considered within the scope of this patent. 

1. A method of calibrating of a differential air pressure system for predicting effective body weight of a user versus system pressure, the method comprising: adjusting pressure inside a chamber that surrounds a portion of a user's body until body weight force on the user's body reaches a target force value; measuring the chamber pressure at the target force value to generate a first (pressure, force) data point; and using the first (pressure, force) data point with at least one other (pressure, force) data point to determine a relationship between body weight force experienced by the user and pressure in the chamber.
 2. The method of claim 1, wherein the target force value is a preset force value.
 3. The method of claim 1, wherein one of the at least one other (pressure, force) data point used in determining the relationship is a body weight of the user measured at ambient pressure.
 4. An apparatus to predict effective body weight of a user as a function of system pressure, the apparatus comprising: a differential air pressure system comprising a chamber configured to receive and surround at least a portion of a user's body; and processing logic coupled with the differential air pressure system, wherein the processing logic is configured to adjust pressure in the chamber until body weight force on the user reaches a target force value, measure the chamber pressure at the target force value to determine a first (pressure, force) data point, and to determine body weight force experienced by the user as a function of pressure in the chamber using the first (pressure, force) data point.
 5. A method of calibrating a differential air pressure system, the method comprising: adjusting pressure in a chamber of a differential air pressure system, the chamber surrounding at least a portion of a user's body; receiving a pain indication supplied by the user as a function of pressure; and constructing a pressure versus pain relationship for the user.
 6. The method of claim 5, wherein the differential air pressure system comprises an exercise machine, and the pressure versus pain relationship is used to control operation of the exercise machine.
 7. The method of claim 6, wherein the exercise machine comprises a treadmill, and the pressure versus pain relationship is used to control at least one of a speed of the treadmill and an incline of the treadmill.
 8. The method of claim 6, wherein the exercise machine comprises a stepper machine, and the pressure versus pain relationship is used to control a resistance of the stepper machine.
 9. The method of claim 6, wherein the exercise machine comprises a stationary bicycle, and the pressure versus pain relationship is used to control a resistance of the stationary bicycle.
 10. An apparatus to predict effective body weight of a user versus system pressure, the apparatus comprising: a differential air pressure system comprising a user interface and a chamber configured to receive and surround at least a portion of a user's body; and a processor coupled with the differential air pressure system, the processor configured to adjust pressure in the chamber, to receive a pain indication from the user via the user interface, and to construct a pain versus chamber pressure relationship for the user.
 11. The apparatus of claim 10, wherein the pain versus chamber pressure relationship is used to control operation of an exercise machine included in the differential air pressure system.
 12. A method of calibrating a differential air pressure system for predicting effective body weight of a user versus system pressure, the method comprising: surrounding at least a portion of a user's body with a chamber of a differential air pressure system, wherein the differential air pressure system comprises a sensor configured to sense whether the user's body within the chamber is in physical contact with a surface; adjusting pressure in the chamber until a lift-off pressure is reached, the lift-off pressure being a pressure at which the sensor detects a break in the physical contact between the user's body and the surface; and using the lift-off pressure to calibrate pressure in the chamber.
 13. The method of claim 12, wherein the lift off pressure can be used to determine a chamber pressure required to result in a desired effective body weight for the user.
 14. The method of claim 12, wherein the lift off pressure used to determine a maximum safety chamber pressure for the user to prevent lift off during usage.
 15. An apparatus to predict effective body weight of a user versus system pressure, the apparatus comprising: a differential air pressure system that includes a chamber to receive and surround at least a portion of a user's body and a sensor configured to detect whether the user's body within the chamber is in physical contact with a surface; and a processor coupled with the differential air pressure system, the processor configured to inflate the chamber of the differential air pressure system, and to measure a lift-off pressure at which the sensor detects that physical contact between the user's body and the surface has been broken.
 16. A method of calibrating a differential air pressure system for predicting effective body weight of a user versus system pressure, the method comprising: using gas to pressurize a chamber in a differential air pressure system, the chamber surrounding at least a portion of a user's body; and using a flow rate of gas into and/or out of the chamber to determine pressure in the chamber.
 17. The method of claim 16, comprising using an exhaust valve position or opening to determine pressure in the chamber.
 18. The method of claim 16, comprising using voltage and/or current drawn by a blower pumping gas into the chamber to determine a pressure in the chamber.
 19. A method of calibrating a differential air pressure system for predicting effective body weight of a user versus system pressure, the method comprising: measuring an effective body weight of a user having at least a portion of the user's body surrounded by a chamber of a differential air pressure system by measuring a startup current and/or voltage of a motor of an exercise machine supporting the user's body within the chamber; and correlating the effective body weight of the user with pressure in the chamber.
 20. The method of claim 19, comprising measuring pressure in the chamber using a flow rate of gas into and/or out of the chamber. 